@article{FrancoPomerance1995,
  author    = {{Zachary Franco and Carl Pomerance}},
  title     = {{On a Conjecture of Crandall Concerning the $qx  +  1$ Problem}},
  journal   = {{Math. Comp.}},
  year      = {{1995}},
  volume    = {{64}},
  pages     = {{1333--1336}},
  note      = {{MR9 5j:11019}},
}